Diesel engine runaway is a serious and fatal threat when operating diesel-powered equipment in hazardous environments. Independent tests have shown that a diesel engine can runaway in as little as 3 seconds, causing it to become a potential ignition source for flammable vapors present in the environment. With only seconds to react, it’s vital that your air shut off system activates as quickly and safely as possible.
Automatic air shut off systems, as opposed to manual air shut off systems, are the safest and most reliable option when it comes to protecting your diesel engines. This video from AMOT’s Ask the Expert series explains the benefits that an automatic system brings to your equipment.
Why an Automatic System?
As mentioned earlier, a diesel engine can runaway in as little as 3 seconds of even low concentration levels of gas being sucked into the engine. As the engine races, and the RPMs rise, not only is it human nature to run away, but it’s also the recommended action to take as suggested by oil & gas safety groups, OSHA and STEPS (source: https://www.nationalstepsnetwork.com/hazard-alerts/2017/5/31/mobile-engine-hazard-alert). If utilizing a manual system, this requires someone to do the opposite and physically approach the runaway engine and manually activate the valve.
How Do They Operate?
An automatic system continually monitors the engine’s RPMs. If a hydrocarbon vapor enters the air intake system and the RPMs exceed the set limit, a speed switch activates the valve to snap shut. In contrast, a manual system requires someone to flip a switch or pull a cable to activate the valve in the event of a runaway situation.
Required by Law
In some instances, you have no option, but to install an automatic air shut off system. In Canada for example, all diesel engine highway tank trucks or portable tanks containing dangerous goods (class 2.1, primary class, or subsidiary class 3) must be equipped with an automatic engine air shutoff device to prevent diesel engine runaway in the event of exposure to combustible vapors (source: https://www.tc.gc.ca/eng/tdg/moc-highway-csab622-309.html). However, if given a choice, an automatic air shut off system is the only reliable method to stop an engine once it has begun to overspeed.
The Safest, Most Reliable Option
There’s no denying that diesel engines can be dangerous in hazardous environments. However, installing the proper automatic air shut off system helps create a safer work environment.
Learn more about air shut off systems in our blog "How To Prevent Diesel Engine Runaway" and contact AMOT if you would like help selecting the correct automatic system for your application.
